Department of Anatomy and Neurobiology, Tongji University School of Medicine, Shanghai 200092, China.
Chin Med J (Engl). 2013 Apr;126(7):1302-9.
Our previous studies have indicated that the beneficial effects of grafting neural stem cells (NSCs) overexpressing glial cell line-derived neurotrophic factor (GDNF) in rats after stroke. However, the underlying mechanisms are highly debatable. In this study, we investigated whether neurogenesis, Akt, and extracellular signal-regulated kinase 1/2 (Erk1/2) signaling were involved in this process.
Transient ischemic stroke were induced by occluding middle cerebral artery for 2 hours and reperfusion. At 3 days after reperfusion, GDNF/NSCs, NSCs, and vehicle were administered. Immunohistochemical staining was used to evaluate neurogenesis by nestin antibody; phosphorylation of Akt and Erk1/2 was investigated by Western blotting analysis.
Transplantation of GDNF/NSCs and NSCs significantly increased nestin-positive cells compared to control group (vehicle) from 1 to 7 weeks after reperfusion, and GDNF/NSCs showed stronger effect than NSCs at 2 and 3 weeks after reperfusion. Meanwhile, enhanced phosphorylation level of Erk1/2 was observed in the GDNF/NSCs and NSCs groups compared with control group, and phosphorylation level of Erk1/2 in GDNF/NSCs group was remarkably higher than that of NSCs group at any given time. In contrast, expression of mitogen-activated protein kinase phosphatase-1 (MKP-1), known as inhibitor of Erk1/2 signaling, was significantly decreased in the GDNF/NSCs and NSCs groups compared with the control group. Moreover, much enhanced and prolonged phosphorylation level of Akt of GDNF/NSCs group was detected compared with control and NSCs group.
Grafting GDNF/NSCs enhances neurogenesis and activates Akt and Erk1/2 signaling, that may provide the potential for GDNF/NSCs in stroke treatment.
我们之前的研究表明，在大鼠中风后移植过表达胶质细胞源性神经营养因子（GDNF）的神经干细胞（NSCs）具有有益作用。然而，其潜在机制仍存在较大争议。本研究旨在探讨神经发生、Akt 和细胞外信号调节激酶 1/2（Erk1/2）信号是否参与这一过程。
通过阻断大脑中动脉 2 小时再灌注诱导短暂性脑缺血。再灌注后 3 天，给予 GDNF/NSCs、NSCs 和载体。用巢蛋白抗体进行免疫组织化学染色来评估神经发生；通过 Western blot 分析来研究 Akt 和 Erk1/2 的磷酸化。
与对照组（载体）相比，移植 GDNF/NSCs 和 NSCs 可显著增加再灌注后 1 至 7 周的巢蛋白阳性细胞数，且 GDNF/NSCs 在再灌注后 2 和 3 周的效果强于 NSCs。同时，与对照组相比，GDNF/NSCs 和 NSCs 组的 Erk1/2 磷酸化水平增强，GDNF/NSCs 组的 Erk1/2 磷酸化水平在任何给定时间均显著高于 NSCs 组。相比之下，GDNF/NSCs 和 NSCs 组的丝裂原激活蛋白激酶磷酸酶-1（MKP-1）的表达，即 Erk1/2 信号的抑制剂，明显低于对照组。此外，与对照组和 NSCs 组相比，GDNF/NSCs 组的 Akt 磷酸化水平显著增强且持续时间更长。
移植 GDNF/NSCs 可增强神经发生并激活 Akt 和 Erk1/2 信号，这可能为 GDNF/NSCs 在中风治疗中的应用提供潜力。
